This is just a quick note that might help someone searching for this information in the future.
My Digital Equipment Corporation VT52 worked, but if it were powered on for a few hours, it would fail and start clicking incessantly (that’s the sound of the relay it uses for its bell).
As the months rolled by, it stopped working entirely – it would start its clicking as soon as it was turned on.
The problem ended up being corroded IC sockets. There are four ROM chips that hold the VT52’s microcode. They are the only socketed chips on the VT52’s circuit boards, so they’re easy to find. I put stickers on them to label their positions, removed them, de-soldered the sockets, and soldered in new ones.
It’s really important not to damage the PCB while de-soldering. I have a Hakko FR-301 de-soldering tool. It’s a big expense if this is the only time you’ll use it, but I’m glad I didn’t have to futz around with a soldering iron.
